This invention relates generally to conveyor sortation systems and, in particular, to a positive displacement sorter of the pusher shoe and slat configuration.
Positive displacement sortation conveyors are known having a main conveying surface and diverter shoes that are generally used to displace articles laterally on the main conveying surface, such as when the articles are to be diverted upon one or more spur conveyor lines typically placed at an angle to the main conveying surface. Such conveyors may include a pair of endless chains and a plurality of members, such as slats, connected at their opposite ends to the chains in order to provide a moving conveyor surface. Each slat, or every other slat, is fitted with a pusher or diverter shoe mounted in a manner such that the shoe may glide laterally across the slat. Movement of the shoe is guided by a guide track beneath the conveying surface. At the loading end of the sortation system, the shoes have a particular orientation with respect to the conveying surface. When an article is to be diverted to a particular spur line, a diverter assembly is actuated to switch a portion of the shoes adjacent the article onto one or more diagonal tracks causing the effected shoes to glide across the slats to divert the article. Examples of such positive displacement sorters include commonly assigned U.S. Pat. Nos. 4,738,347 and 5,127,510. Other examples include U.S. Pat. Nos. 3,361,247; 5,409,095; and 4,884,677; and European Published Patent Applications EP 0 602 694 B1 and EP 0 444 734 A1.
In many instances, sortation conveyors are driven by rotary motors operatively connected to sprockets which propel the chains. As the application in which the sortation conveyors are used becomes increasing large, the size of the rotary motors must correspondingly increase in order to provide sufficient power to propel the longer conveying surface, as well as achieve the desired throughput. As the size of the motors and sprockets increases in order to meet the additional power requirements, the noise issued from the rotary motor, as well as the sizes of the sprockets and chains, correspondingly increase.
There is a long-felt need to increase the throughput of conveyor systems. Sortation conveyors and their associated induction conveyors are often the most challenging portion of the conveyor system to handle increasing demands for article throughput. Increase in throughput can be achieved by increasing the speed of the conveying surface. However, there are difficulties in continuously increasing the speed of the conveying surface. Another way to increase throughput is to decrease the gap between articles while ensuring sufficient gap to allow the articles to be properly diverted to their destination spur. As gaps get smaller to increase throughput, the necessity to maintain control over the gaps increases. Because gaps are established by placement of articles on the conveying surface of the sorter and the articles are placed on the conveying surface of the sorter from an induct conveyor, the requirement for smaller gaps increases the desirability to place and maintain the articles in proper position on the conveying surface of the sorter.
The present invention provides a unique positive displacement sorter apparatus and method of controlling same. Aspects of the present invention may be utilized with conventional motors, and a unique linear motor drive system and method of the present invention may be utilized with other positive displacement sorter configurations than those disclosed herein.
A positive displacement sorter apparatus, according to an aspect of the invention, includes means for defining a plurality of slats that are interconnected, thereby defining an endless web. An upper run of the web defines a conveying surface. The apparatus further including means for defining a plurality of pusher shoes gliding along at least some of the slats to laterally displace articles on the conveying surface. The apparatus further includes secondary means for defining a plurality of linear motor secondaries at the slats, primary means for inducing thrust in the secondaries and thereby propelling the web and control means for controlling the primary means.
The apparatus may include a wheel apparatus for supporting the web, the wheel apparatus having wheels at some of the slats rotating about an axis projecting from an interior of the associated slats. Each of the slats may have an upper surface portion that is substantially planar. Each of the slats may have an outer surface that does not extend above the conveying surface for all orientations of the slats. The primary and secondary means may be either a synchronous linear motor system or a non-synchronous linear motor system. The primary means may be between the upper and lower runs of the web. The secondary means may include magnet plates in the interior of the slats. The primary means may be adjacent an upper run of the web for propelling slats in the upper run and be positioned where the pusher shoe diverter assemblies are not positioned. The primary means may be adjacent a lower run of the web for propelling slats in the lower run from above and produce sufficient thrust to propel the web without elevating the slats in the lower run.
A positive displacement sorter apparatus, according to an aspect of the invention, includes a plurality of interconnected slats defining an endless web, the upper portion of the web defining a conveying surface and pusher shoes gliding along at least some of the plurality of slats to laterally displace articles on the conveying surface. Each of the slats has an outer surface including upper, lower and side surface portions. Either the front or rear surface portion is generally concave. The other of the front or rear surface portions is generally convex. In this manner, adjacent slats have cooperatively faced portions. Among the many advantages that may be achieved, this aspect of the invention provides for generally uniform gaps between the slats irrespective of orientation of the slats, such as when the slats are traveling between upper and lower web portions and the transition portions between the upper and lower web portions.
One of the generally concave and generally convex surface portions may have a first enclosing radius of curvature and the other of the generally concave and generally convex surface portions may have a second enclosing radius of curvature with the first and second enclosing radii having a common locus. At least one of the generally concave and generally convex surface portions may have a planar segment or may have an arcuate segment. The sorter apparatus may include a wheel apparatus for supporting the slats. The wheel apparatus may have a slat-support wheel at a locus of the radius of one of the arcuate portions. The upper surface portion of the slats may be substantially planar. The outer surface of the slats may be at or below the conveying surface for all orientations of the slats.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web having upper and lower runs and transition portions between the upper and lower runs. The upper run of the web defines a conveying surface. Pusher shoes glide along at least some of the plurality of slats to laterally displace articles on the conveying surface. A linear motor propulsion system is provided for propelling the web. The linear motor propulsion system includes at least one motor primary and a plurality of motor secondaries at the slats. The at least one motor primary is between the upper and lower runs. Among the many advantages that may be achieved, the positioning of the at least one motor primary between the upper and lower runs reduces the vertical height of the sorter apparatus. This allows the sorter apparatus to be adapted to an increased number of applications without taking special precautions to accommodate a higher sorter apparatus.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web having upper and lower runs and transition portions between the upper and lower runs. The upper run of the web defines a conveying surface. Each of the slats has a surface configuration. Pusher shoes glide along at least some of the plurality of slats to laterally displaced articles on the conveying surface. The sorter apparatus further includes a support track network and a wheel apparatus moveably supporting the endless web for movement on the support track network. The wheel apparatus includes at least one wheel supporting each slat and couplers for coupling adjacent ones of the slats. A relationship between the at least one wheel and the surface configuration substantially avoids a portion of the surface from extending above the conveying surface while slats are moving between the upper portion and the transition portion. Among the many advantages that may be achieved is the reduction of the likelihood that the outer surface of a slat making a transition to or from the conveying surface may inadvertently dislodge an article from its location.
The surface configuration may include a front and rear surface portion, one being generally concave and the other being generally convex. Each may be generally arcuate having a radius of curvature. The at least one wheel may be at a locus of one of the radii. The upper surface portion may be substantially planar.
A positive displacement sorter apparatus, according to an aspect of the invention, includes a plurality of interconnected slats defining an endless web, an upper surface portion of the web defining a conveying surface, and pusher shoes gliding along at least some of the plurality of slats to laterally displace articles on the conveying surface. A linear motor propulsion system includes at least one motor primary adjacent the web and a plurality of motor secondaries with the slats defining a magnetic interface between the at least one motor primary and any of the motor secondaries passing that motor primary. A lateral stabilizer is provided between each of the pusher shoes in the corresponding ones of the slats. Among the many advantages that may be achieved, this provides the lateral stabilizer without interfering with the air gap between the at least one motor primary and the motor secondaries.
The lateral stabilizer may include a portion of the shoe that is laterally extending and projecting in a recess in the slat, with the lateral stabilizer being substantially outside of the magnetic interface. Each of the slats may have a surface including a lower surface portion. The lateral stabilizer may be at the lower surface portion. The motor secondaries may be adjacent the lower surface portion. The lateral stabilizer may be forward of the magnetic interface with respect to movement of the web or may be rearward of the magnetic interface with respect to movement of the web. The motor secondaries may be fixed within the associated slats.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web. An upper portion of the web defines a conveying surface. Pusher shoes glide along at least some of the plurality of slats to laterally displace articles on the conveying surface. A support track network is provided, and a wheel apparatus moveably supports the endless web for movement on the support network. Each of the slats is made up of an outer wall having an upper wall portion and a lower wall portion. Each of the slats is mounted to the wheel apparatus with the associated wheel rotating about an axis projecting to the interior of the associated slat. Among the many advantages that may be achieved, this keeps the mass of the slats close to the support track network, thereby reducing acceleration forces on the web as the web transitions between the upper and lower runs.
The wheel apparatus may further include a plate apparatus coupling adjacent slats. The wheel may be rotatably supported by a shaft connected with adjacent ones of the plates, thereby pivotally joining adjacent slats to pivot at the axis mounting the wheel. The mounting member may be substantially closer to the lower wall portion than to the upper wall portion. Among the many advantages that may be achieved, this further shortens the distance between the bottom of the slat and the track apparatus, thereby allowing for a lesser radius at the transition portions of the web, thereby minimizing vertical height of the sorter apparatus. This is especially advantageous for pusher shoes having elongated members below each of the pusher shoes because it allows the radius of the transition portion to be reduced without allowing interference between the elongated members. A plurality of diverter assemblies may be provided for selectively laterally diverting the pusher shoes. The diverter assemblies interact with elongated members.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web having upper and lower portions and transition portions between the upper and lower portions. The upper portion of the web defines a conveying surface. Pusher shoes glide along at least some of the slats to laterally displace articles on the conveying surface. A support track network has upper and lower track portions and transition track portions between the upper and lower track portions. A wheel apparatus moveably supports the endless web for movement on the support track network. At least one of the support track network transition track portions has a support surface that is a non-circular curve. Among the many advantages that may be achieved, this allows acceleration forces on the slats and shoes to be controlled as the slats and shoes move through the transition portion having this configuration, thereby allowing the acceleration forces to be controlled in a manner that may reduce the noise of the web movement.
The support surface may be substantially non-symmetrical about a horizontal axis. The support surface may have generally larger radii of curvature above the horizontal axis than below the horizontal axis, or vice versa. The support surface may be substantially symmetrical about a horizontal axis. The transition track portion may include a moveable portion to accommodate expansion and contraction of the web. An expansion joint may be provided between the moveable portion and the remainder of the support track network to provide track network continuity between the moveable portion and the remainder of the support track. A force-producing member may apply a force on the moveable portion, which may be a substantially constant force irrespective of position of the moveable portion.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web having upper and lower portions and transition portions between the upper and lower portions. The upper portion of the web defines a conveying surface. Pusher shoes glide along at least some of the plurality of slats to laterally displace articles on the conveying surface. A support track network and a wheel apparatus moveably support the endless web for movement on the support track network. The support track network includes a stationary portion, a moveable portion to accommodate expansion and contraction of the web and an expansion joint between the stationary and moveable portions to provide track network continuity between the stationary and moveable portions. Among the many advantages that may be achieved, this allows the wheel apparatus to maintain contact with the support track network.
The expansion joint may include a plurality of interlaced fingers. A force-producing member may apply a force on the moving portion. The force-producing member may produce a substantially constant force irrespective of the position of the moveable portion. The moveable portion may be generally horizontally moveable.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web having upper and lower portions and transition portions between the upper and lower portions. The upper portion of the web defines a conveying surface. Pusher shoes glide along at least some of the plurality of slats to laterally displace articles on the conveying surface. A support track network and a wheel apparatus moveably support the endless web for movement on the support track network. The support track network includes a stationary portion, a moveable portion and a force-producing member. Movement of the moveable portion with respect to the stationary portion accommodates expansion and contraction of the web. The force-producing member applies a substantially constant force on the moveable portion irrespective of position of the moveable portion. Among the many advantages that may be achieved, this provides a more consistent tension on the web, which, in turn, provides for more consistent movement of the web irrespective of the expansion or contraction of the web.
The force-producing member may apply a substantially horizontal force on the moveable portion. The force-producing member may include a weight apparatus and a cable system for translating gravitational force produced by the weight apparatus to an outwardly directed force on the moveable portion. The weight apparatus may have a mass that is adjustable. The sorter apparatus may include an expansion joint between the moveable portion and the stationary portion.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web having upper and lower portions and transition portions between the upper and lower portions. The upper portion of the web defines a conveying surface. Pusher shoes glide along at least some of the plurality of slats to laterally displace articles on the conveying surface. The apparatus includes a support track network and a wheel apparatus moveably supporting the endless web for movement on the support track network. A plurality of diverters and associated diverter rails are provided for selectively displacing ones of the pusher shoes laterally of the conveying surface to displace articles on the conveying surface. A frame is provided for supporting the support track network, the diverters and diverter assemblies. The frame includes at least two longitudinal horizontal members. The horizontal members define fastener channels along the horizontal members. The diverters and diverter rails can be selectively mounted at chosen positions along the frame by fasteners engaging the fastener channels. Among the many advantages that are achieved, this allows the sorter apparatus to be designed from common assemblies irrespective of the application by allowing the location of the spurs, and the associated components to be positioned along the support frame without the necessity for special configuration of the support frame.
The horizontal members may be extruded members. The frame may include support legs, which may be selectively mounted at chosen positions along the frame by fasteners engaging the fastener channels. The sorter apparatus may include a plurality of cross braces between the horizontal members. The cross braces may be mounted at chosen positions along the frame by fasteners engaging the fastener channel. The sorter apparatus may include a linear motor propulsion system for the web. The linear motor propulsion system may include at least one motor primary adjacent the web and a plurality of motor secondaries with the slats. The at least one motor primary may be selectively mounted at a chosen position along the frame by fasteners engaging the fastener channels.
A positive displacement sorter apparatus, according to an aspect of the invention, includes a plurality of interconnected slats defining an endless web, an upper portion of the web defining a conveying surface and pusher shoes gliding along at least some of the plurality of slats to laterally displace articles on the conveying surface. A closed-loop propulsion system for the endless web is provided. The propulsion system includes at least one motor, a web sensor for sensing movement of the web and a control that is responsive to the web sensor to excite the at least one motor in a manner that reduces speed fluctuations resulting from variations in article loading of the endless web. Among the many advantages that are achieved, this allows more accurate positioning of articles on the conveying surface from the upstream conveying system, such as an induction conveyor, by ensuring a more accurate speed relationship between the upstream conveying system and the sorter conveying surface by providing a more closely regulated speed of the sorter conveying surface. This feature is especially beneficial as the loading on the conveying surface varies substantially.
The web sensor may be a slat sensor, such as a proximity sensor, an optical sensor, an ultrasonic sensor, a microwave sensor, or the like. The web sensor may identify transitions between the slats. The web sensor may further identify at least one particular slat. This may be accomplished by a Hall-effect sensor and at least one magnet in a particular slat. The web sensor identifies the at least one particular slat by identifying the magnet with the Hall-effect sensor. The web sensor may further identify multiple particular slats.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web having upper and lower portions and transition portions between the upper and lower portions. The upper portion of the web defines a conveying surface. Pusher shoes glide along at least some of the plurality of slats to laterally displace articles on the conveying surface. A linear motor propulsion system is provided for propelling the web. The propulsion system includes at least one motor primary adjacent the web and a plurality of motor secondaries with the slats. The at least one motor primary propels slats in the lower portion from above. Among the many advantages that are achieved, this allows the linear motor primary to be positioned in a manner that minimizes vertical height of the apparatus.
The linear motor propulsion system may be configured to produce sufficient thrust to propel the web without substantially elevating the slats in the lower portion. Among the many advantages that are achieved, this allows the linear motor primary to be positioned where desired without resulting in an increase in noise from elevating the slats against gravitation resulting in a noise created by the motion of the web. A support track network and a wheel apparatus moveably supporting the endless web for movement on the support track network may be provided, wherein the support track network supports the lower run from below the slats. The apparatus may further include a plurality of diverter assemblies to selectively divert the pusher shoes and at least one other motor primary propelling slat in the upper portion from below the slats in the upper portion. The at least one other motor primary may be positioned where the diverter assemblies are not positioned.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web and an upper run of the web defining a conveying surface. Pusher shoes glide along at least some of the plurality of slats to laterally displace articles on a conveying surface. A linear motor propulsion system propels the web. The linear motor system includes at least a motor primary and a plurality of motor secondaries at the slats. The motor secondaries include magnet plates that are retained in the associated slats by being fixed from within the associated slats. Among the many advantages that are achieved, this facilitates apparatus of the secondaries to the associated slats and secures positioning of the magnet plates within the slats.
The motor magnet plates may be fixed within the associated slats by interference fit. The motor magnet plates may be fixed within the associated slats by deforming portions of the slats. The motor magnet plates may be fixed within the associated slats by dimensional interference between the motor magnet plates and the associated slats. The motor magnet plates may be fixed within the associated slats by inserts in the slats, or adhesive, or by welding. The slats may be extruded and may include pockets for the motor magnet plates. A plurality of motor magnet plates may be provided in each of the slats. This allows the slat to be propelled from linear motor primaries on opposite sides of the web surfaces.
Any of the positive displacement sorter assemblies discussed above may include a linear propulsion system for the web, which may be chosen from a synchronous linear motor system or a non-synchronous linear motor system. The propulsion system may include at least one motor primary adjacent the web and a plurality of motor magnet plates with the slats. The at least one motor primary may be between the upper and lower runs of the web. The motor magnet plates may be in the slats. A plurality of diverter assemblies may be provided to selectively laterally divert the pusher shoes. The at least one motor primary may be adjacent an upper run of the web and adapted to propel slats in the upper run. The at least one motor primary may be positioned where the diverter assemblies are not positioned. The at least one motor primary may be adjacent the lower run of the web and adapted to propel slats in the lower run from above. The at least one primary motor may be configured to produce sufficient thrust to propel the web without substantially elevating the slats in the lower run.
A method of sorting articles, according to an aspect of the invention, includes providing a plurality of interconnected slats defining an endless web, an upper portion of the web defining a conveying surface and providing pusher shoes gliding along at least some of the plurality of slats to laterally displace articles on the conveying surface. The method further includes providing a web sensor and sensing movement of the web with the web sensor and providing a propulsion system comprising at least one motor. The method further includes exciting the at least one motor at least as a function of an output of the web sensor thereby reducing speed fluctuations resulting from variations in article loading of the endless web. Among the many advantages that are achieved, this method provides more accurate positioning of articles on the conveying surface from the upstream conveying system, such as an induction conveyor, by assuring a more accurate speed relationship between the upstream conveying system and the sorter-conveying surface.
The web sensor may be a slat sensor, such as a proximity sensor, an optical sensor, an ultrasonic sensor, a microwave sensor, or the like. The method may further include identifying transitions between slats with the proximity sensor. The method may further include identifying at least one particular slat with the web sensor. The web sensor may include a Hall-effect sensor and the at least one particular slat may include a magnet, wherein identifying the at least one particular slat may include identifying the magnet with the Hall-effect sensor.
The propulsion may be a linear motor propulsion system and the at least one motor may be at least one linear motor primary and a plurality of motor secondaries with the slats. The at least one linear motor primary may be a plurality of linear motor primaries and the method may further include exciting the plurality of linear motor primaries as a function of the output of the web sensor. The exciting of the plurality of linear motor primaries may include supplying digital signals to the plurality of linear motor primaries and adjusting the linear motor primaries with the digital signals.
A method of sorting articles, according to another aspect of the invention, includes providing a plurality of interconnected slats defining an endless web having upper and lower runs and transitions runs between the upper and lower runs. The upper run of the web defines a conveying surface. The method further includes providing pusher shoes gliding along at least some of the plurality of slats. The method further includes providing the linear motor propulsion system for propelling the web. The propulsion system includes at least one motor primary adjacent the web and a plurality of motor secondaries with the slats. The method further includes propelling slats in the lower run from above with the at least one motor primary. The method further includes laterally displacing articles on the conveying surface with the pusher shoes. Among the many advantages that are achieved, this method allows the linear motor primary to be positioned where desired.
The method may further include producing sufficient thrust to propel the web without elevating the slats in the lower portion. This reduces noise from elevating the slat against gravitation resulting in a noise created by the motion of the web. Another motor primary may be provided to propel slats in the upper run from below the slats in the upper run. Diverter assemblies may be provided to laterally divert the pusher shoes. The at least one other motor primary may be between adjacent ones of the diverter assemblies.
A method of sorting articles, according to another aspect of the invention, includes providing a plurality of interconnected slats defining an endless web having upper and lower runs and transition portions between said upper and lower runs. The upper run of the web defining a conveying surface. Pusher shoes are provided gliding along at least some of the plurality of slats. A linear motor propulsion system is provided including at least one motor primary and a plurality of motor secondaries at the slats. The at least one motor primary is positioned between the upper and lower runs, and the plurality of motor magnet plates are with the slats. The method further includes laterally displacing articles on the conveying surface with the pusher shoes. Among the many advantages that are achieved, this method allows sorting of articles within a vertical space that is small. The magnet plates may be in the slats.
Any of the above-identified methods may include providing a linear motor propulsion system that is chosen from one of a synchronous linear motor system and a non-synchronous linear motor system. The method may further include providing the at least one motor primary between upper and lower runs of the web and may include providing magnet plates in the slats. The method may further include providing a plurality of diverter assemblies and selectively diverting the pusher shoes with the diverter assemblies. The at least one motor primary may be provided adjacent an upper run of the web and propelling slats in the upper run from below. The at least one motor primary may be positioned where the diverter assemblies are not positioned. The at least one motor primary may be positioned adjacent the lower run of the web and propelling slats in the lower run from above with the at least one motor primary. The at least one motor primary may provide sufficient thrust to propel the web without elevating the slats in the lower run. The method may include propelling the web at a reduced speed when articles are not being provided to the conveying surface. The method may further include providing magnet plates in the slats and fixing the magnet plates from within the associated slats. The magnet plates may be fixed within the associated slats by at least one of interference fit, inserts, adhesive or welding.